I don’t know of any direct ways to do it, but that’s only after a very quick search so there might be something hidden deep down in the source code that I’ve missed.

If I had to do this, I’d do it by wrapping the calls to get_sidebar() in a call to strip_tags() and passing in the allowed tags like p, li, ul, etc. It’s a bit of a hacky work-around, but it’s able to be done that way.